Chlorine vs Bromine: Which is Better?

Pool chlorine may be the hottest thing in swimming pool sanitation, but did you know that there are many other options to choose from?

One of those options that people sometimes talk about is pool bromine. Bromine and chlorine are similar in many ways, but they can’t be used interchangeably without a noticeable difference.

So what is pool bromine and how does it differ from pool chlorine?

Since we’re swimming pool experts at Best Pool Services, we thought we would share what we know about these two pool sanitizers to help you learn the differences and choose the right one for your pool or spa.

Let’s start with a brief overview of chlorine.

What is Pool Chlorine?

Pool chlorine is also known as hypochlorous acid and is widely used to sanitize indoor and outdoor pools. Chlorine works well as a sanitizer because it maintains a residual in the water, meaning it keeps the water sanitized over a period of time (typically a few hours or overnight). Chlorine is also an oxidizer (destroys contaminants in the water) and it acts as an algicide to keep common types of algae at bay.

The only true form of chlorine for pool sanitation is gas chlorine. Chlorine in its natural state is a gas, so all other chlorine products like tablets, liquid, and granules will vary in their composition. However, they all basically do the same thing: release hypochlorous acid to kill and inactivate pathogens in the water.

Forms of pool chlorine:

Tablets
Granules
Liquid
Gas
Salt (converts to chlorine using a salt chlorine generator)

Pool chlorine tablets

What is Pool Bromine?

Pool bromine is a sanitizer, oxidizer, and algicide that is used in swimming pools and spas. In its original state, bromine is a reddish brown liquid, but for pools, it can be found in tablet, granular, stick, and liquid sanitation products (though you would never use pure elemental bromine in a pool or spa). Any liquid bromine products that you may find are diluted with water and other chemicals for safe handling and better performance.

“Bromine” isn’t true bromine, but the name is used to describe any chemical that releases hypobromous acid into the water. This takes place in two ways:

The two-part system consists of sodium bromine activated by an oxidizer and is typically used in smaller volumes of water (spas).
The solid, dissolvable form of bromine (tablets, granules, etc.) is formed when bromine is bound to an organic molecule.

Chlorine vs Bromine

Bromine and chlorine are both halogens (an element group including Fluorine, Chlorine, Bromine, Iodine, and Astatine) and they belong to the same chemical family. They are both disinfectants, algicides, and oxidizers, but there are a few key differences that separate how they perform. Let’s break them down by category.

Skin Irritation

Skin irritation and rashes can occur after exposure to both chlorine and bromine, but many people say that bromine is much better for the skin. However, according to the National Swimming Pool Foundation, Bromine Itch is the most commonly reported type of chemical rash. Maintaining proper chemical levels for both bromine and chlorine can help to prevent these reactions and any type of related skin irritation or dermatitis.

Eye Irritation

Bromine is well known for being gentler on the eyes, although this varies by person and by the quality of maintenance of the pool or spa. The comfort level for skin and eyes will usually depend on how well the water is monitored and maintained unless the swimmer has a chemical allergy.

Odor

Chlorine is known to have a much stronger odor than bromine, which some may find unpleasant. If you don’t like the strong chlorine smell in your pool, using bromine may be a good solution.

Indoor and Outdoor Pools

Chlorine works well indoors and outdoors, but bromine is sensitive to sunlight and less effective when exposed to UV rays. In fact, according to the NSPF, half of pool bromine can be destroyed by exposure to sunlight in just 60 to 90 minutes. Unlike chlorine, cyanuric acid does not protect bromine from the sun. Because of this, bromine may not be very compatible with a pool UV system.

Available Options

There are more available methods for adding chlorine to the water, including tablets, granules, liquid, gas, and salt. Bromine is mostly limited to solid tablets, granules, and sticks with a few liquid options. Additionally, pure chlorine (gas) is an available pool sanitation method, while pure elemental bromine is not.

Cost

As a whole, bromine is known to be more expensive than pool chlorine. While the price difference isn’t all that noticeable when buying in small quantities, buying in bulk can reveal just how much more bromine is. For example, a 50 pound bucket of chlorine tablets might cost you $150 while a 50 pound bucket of bromine tablets might cost over $300. If you have an outdoor pool and you need to add bromine more often, this will also increase the cost of sanitizing your pool with bromine.

Oxidation

Bromine has many strengths, but it’s not the best oxidizer. Chlorine definitely wins when it comes to oxidation power for your pool or spa (oxidation is the breakdown of contaminants in the water).

Chlorine vs Bromine in Hot Tubs

This is one of the areas in which chlorine and bromine differ the most. Hot tubs and spas maintain high water temperatures, and higher water temperatures can lead to rapid changes in pH levels. Bromine performs better than chlorine at higher temperatures and higher pH levels, often making it the preferred choice for spas.

Pros and cons of chlorine and bromine

Chlorine and bromine each have their benefits and weaknesses, but how they perform for you will depend on your needs and preferences. Remember, if you are allergic to chlorine, bromine is not a good alternative as it belongs to the same chemical family.

As a brief recap, here are the pros and cons of using chlorine and bromine in your pool or spa:

Chlorine

Pros

Readily available
Effectively kills or inactivates pathogens and algae
Multiple use options (tablets, granules, liquid, gas, etc.)
Oxidizes materials in the water
Works in indoor and outdoor pools
Works with all three pool types (with the exception of salt systems)
Maintains a residual concentration in the water

Cons

Can leave a strong smell
May cause eye or skin irritation
Salt chlorine systems can wear down vinyl liner and concrete pools
Can bleach vinyl liners if there is prolonged contact (granules at bottom of pool, etc.)
Chlorine products sometimes contain other ingredients that dilute the amount of available chlorine content

Bromine